In the Journal of The Japanese Society of Applied Physics, Volume 34, L452, 1995, there is disclosed silicon network polymer and the synthesizing method thereof. The synthesizing method uses Wurtz's reaction in which trihalosilane is condensation-reacted with sodium metal.
Further, in Japanese Patent Application Laid-Open No. 3-258834 (1991), there is disclosed straight chain fluorine-containing polysilane and the synthesizing method thereof. This also uses Wultz's reaction.
However, in the prior art, fluorine-containing silicon network polymer has never been synthesized. The reason is that the compounds which can be used for the Wurtz's reaction are limited, and in particular there is no raw material for the fluorine-containing silicon network polymer.
In electronic devices, typically a semiconductor, it is extremely desired to obtain an insulating layer with lower permittivity in order to improve its performance. In order to respond the above-mentioned requirement, there has been studied a plasma TEOS film by a CVD method, a SiOF film, etc. However, in order to form those films, it is necessary to provide a CVD equipment, and further the productivity is low. From such a point of view, prior art uses a coating method to form the insulating layer.
In the Journals of The Japanese Society of Applied Physics, Volume 77, 2796 (1995) and Volume 34, L452 (1995), there are disclosed methods of forming a SiO film by using silicon network polymer. However, because the silicon network polymer containing no fluorine is used, it is impossible to obtain the desired insulating layer with lower permittivity.
Further, because the stability of the straight chain fluorine-containing polysilane is low, it is impossible to form the desired insulating layer even if the methods disclosed in the Journals of Japanese Society of Applied Physics, Volume 77, 2796 (1995) and Volume 34, L452 (1995) are applied.
While organic spin-on-glass (hereinafter, abbreviated as SOG), one of polysiloxane type coating material can provide the insulating layer with relatively low permittivity, the stress is large when hardened. It is impossible to form the desired insulating layer except the insulating layer with thickness of sub-micron order. Further, the workability is low and thus it is apt to crack.
As the semiconductor is highly integrated, the irradiation light of far shorter wave is required for use of photolithography in order to obtain fine wires. While in the photolithography g-line (436 nm), one of the emission characteristics of a mercury lamp was commonly used, recently i-line (365 nm) more suitable to fine working has become more used. The fine working is carried out by using photo resist of which a major component is organic macromolecules containing aromatic ring within its molecules. In the development process of forming patterns, a wet development method due to solvent or a dry etching method due to reactive gas is used.
It seems that the microstructures of semiconductors will be further improved. However, previously the photo resist of which a major component is organic material is not suitable for the lithography which uses the light with wavelength shorter than 350 nm in which it has the self-absorption action against the wavelength shorter than 350 nm.
As main light sources of which the wavelength is equal to or less than 350 nm, there are far-ultraviolet or excimer laser such as KrF (248 nm) or Ar (193 nm). The spotlight centers on the photolithography in which the combination of the light source with short wavelength and polysilane of which sensitivity falls within the short wavelength area are used. However, a pattern forming method which uses these polysilane resist also utilizes a wet development method or a dry etching method in which reactive gas is used. (see SPIE, Vol.1466, P211 (1991))
Further, in order to form active elements such as transistors, diodes, etc. on the substrate of a semiconductor, it is necessary to perform more complicated processes such as oxidation reaction, impurity diffusion, ion implantation, etc. in addition to the above-mentioned wiring forming process.
In addition, in order to form light wave-guiding passage, etc., it is necessary to pass through furthermore complicated processes such as etching, coating, etc. Accordingly, there are many problems in the efficiency of manufacturing, the yields, etc.